High observation accuracy is required of an optical sensor aboard a satellite or the like. To meet the requirement, an error of the optical axis (pointing direction) of an optical system including a lens, a minor, and others in such an optical sensor is measured to adjust alignment in the optical sensor.
For example, an alignment measurement apparatus disclosed in Patent Literature 1 measures an error of an optical axis of a reflective condenser optical system in the optical sensor. This alignment measurement apparatus includes a laser light output unit for outputting laser light in multiple directions and a plurality of light receiving elements for receiving through a minor the laser light output by the laser light output unit. The alignment measurement apparatus detects an error of an optical axis in the optical sensor based on the light signal received by the plurality of light receiving elements.